A novel transcriptional regulator Atr R of Aspergillus fumigatus is required for azole resistance, hypoxia growth, and expression of ABC transporter gene cdr1B

Ref ID: 19541

Author:

D Hagiwara1*, K Shimizu1, A Ohba2, K Kamei1, T Gonoi1, S Kawamoto1, K Gomi2

Author address:

1Medical Mycology Research Center, Chiba University, Chiba, Japan
2Graduate School of Agriculture, Tohoku University, Sendai, Japan

Full conference title:

6th Advances Against Aspergillosis 2014

Abstract:

Purpose:
Although azoles are major agents for treatment of aspergillosis, resistance to the drugs in a main
causative species Aspergillus fumigatus is prevailing in this decade. In most cases, amino acid
substitutions are found in an azole-target protein Cyp51A of resistant strains. Although much
attention has been paid to the Cyp51A mutation regarding azole resistance, molecular mechanism
underlying regulation of Cyp51A as well as transporters that contribute to efflux and sequestration
of azole is obscure. In a study of related species Aspergillus oryzae, we have found that a putative
transcription factor AtrR was involved in azole resistance and the expression of transporter genes.
We here characterized the corresponding AtrR of A. fumigatus with regard to azole resistance,
growth under hypoxic condition, and regulation of ABC transporter gene expression.
Methods:
We constructed an atrR gene deletion strain and the complemented strain (Co-atrR). To characterize
atrR mutant, growth in the presence of azole drugs, expression of cyp51A and the other genes of
ergosterol biosynthesis pathway (erg3, erg24A, and erg25A), and growth under hypoxic condition
(approximately 1% O2) were investigated. Furthermore, expression of the ABC transporter Cdr1B/
AbcC that was recently reported to be associated with azole resistance was also examined.
Results:
Deletion of atrR resulted in an increased sensitivity to azole drugs such as miconazole, itraconazole,
and ketokonazole, but not to micafungin and amphotericin B in A. fumigatus. Quantitative real-time
PCR analysis showed that cyp51A expression in the atrR mutant was significantly low. In addition,
the gene expression levels of erg3, erg24A, and erg25A in the mutant were lower than those in WT
(Af293). The atrR mutant grew comparable to WT under normoxic condition. However, the mutant
was unable to grow under hypoxic condition, whereas WT strain could grow normally. The cdr1B
expression was induced in response to azole addition in WT. In atrR mutant, however, the induction
was not observed and the basal level of the cdr1B expression was decreased.
Conclusion:
Results of the present study indicate that AtrR of A. fumigatus plays a crucial role in azole resistance
by regulating cyp51A expression as well as cdr1B that were involved in azole resistance. AtrR was
also shown to be required for hypoxic growth, suggesting an important role in pathogenicity.
NOTE: THIS ABSTRACT HAS BEEN SELECTED FOR ORAL PRESENTATION.

Abstract Number: 68

Conference Year: 2014

Link to conference website: http://www.AAA2014.org

New link: NULL

Conference abstracts, posters & presentations

Showing 10 posts of 17325 posts found.

  • Title

    Author

    Year

    Number

    Poster